Preference test, odor

Fig. 23.1 Results of the odor preference test in a Y-maze (A). Female mice carrying lesions in either the MOE (B) or VNO (C) were given a choice between volatile odors derived from an intact or a gonadectomized male...

As to sympatric species, some points are important. First, the differences in responses that we observed in these experiments to urine of sympatric, closely related species were similar to those found in previous studies in which preferences were examined between conspecific urine and urine of sympatric species that were unrelated to the subjects (Apodemus flavicollis, Cricetulus migratorius, Sokolov et al. 1990). Secondly, M m. musculus and M spicilegus males preferred the odors of estrous females over males when tested with either urine of a conspecific female and a conspecific male or urine of a heterospecific female and a heterospecific male (Sokolov, Kotenkova Lyalyukhina, 1985, Table 2). 

Hepper (1994) reported scent-mediated kin recognition in adult dogs separated from their mother for approximately 2 years. Unaware of Hepper s report until recently, we repeated his experiment (our Study 1) using a two-choice odor preference test much like Hepper s and that used by Mekosh-Rosenbaum et al. (1994). 

It was found that C females preferred odor stimuli from the dissimilar B6 males over those from C males (mean SEM 257 18 vs. 197 17 s per 10 min. trial, n=12, p=0.03 Wilcoxon matched pairs test). B6 females preferred the odors from the males of their own B6 strain over those from C males (268 7 vs. 242 6 s, n=18, p=0.05). 

If testosterone is an important determinant of the attractiveness and potential quality of male mates, then females are expected to prefer the odors of intact males (i.e., sham-operated) over the odors of castrated males. Odor tests conducted using young (120—150 d of... 

Figure 1. The amount of time (mean 1 S.E.) that females spent investigating odors of intact and castrated males during the entire 15 minutes of odor-preference tests ( Significant difference between means, P < 0.05, Signifi-cant difference between means, P < 0.01, Wilcoxon paired rank sum test).

If the odors from male prairie voles play a primary role in mate selection by females, then males whose odors are preferred are expected to be chosen preferentially as mates. We tested our prediction using the 17 females from the odor-preference trials in which odors from control and food-deprived males were tested. These females were then observed and videotaped while in an enclosure with an unfamiliar pair of stimulus males (i.e., control and post-weaning food-deprived). The relative attractiveness of the odors from each male in a pair, and testosterone level, had previously been determined when each pair was used as scent-donors in an odor-preference test with another female. Because exposure to a female may affect male hormone levels, we determined the testosterone level of males the day after their use in a mate-preference test (A 61 d of age). There was no consistent pattern of change in testosterone level of males after exposure to a female, so we used the testosterone levels measured after the odor preference tests (51 d of age Figure 3) for analyses of female association and mate preferences. 

For the sex discrimination tests one sample jar contained a male and the other contained a female. Plethodon glutinosus, P. jordani, and P. aureolus were used 72 males and 36 females among these species were tested. Both males and females significantly preferred the odors of females over males (Dawley, 1984a). All tests were done during the... 

An experiment in progress in my laboratory has yielded results that indicate that prepubertal female mice prefer the odor of grouped females relative to other mouse odors the pattern shifts to avoidance of the odor from grouped females when the test subjects are 40-55 days of age, at and just after puberty. As adults, these mice do not exhibit a preference for, or avoidance of, the odor of grouped females. 

Mountain beaver do not adapt well to food deprivation, but they can be trained to respond to a preferred food (e.g., apple). Therefore, mountain beaver can be accustomed to a feeding schedule that includes apples and then this highly preferred food is treated with stimuli or placed adjacent to test odors during test trials (Epple et al. 1993, 1995 Nolte et al. 1995a, 1995b). 

Table III. Odor preference test results when 20 candidate materials were compared with investigation time toward the familiar food odor (Purina Laboratory Rat Chow).

However, some studies report only marginal effects of early odor exposure on adult odor preference. These contradictory findings may be due to differences either in the behavioral measures or species tested. For example, although Moore, Jordan and Wong (1996) observed decreases in ejaculation latencies similar to those observed by Fillion and Blass (1986), the author found no effect of early odor... 

Olfactory sensitivity for one individual varies about factor three due to climatological, physiological, environmental reaons etc. The sensory sensitivity also varies from odorant to odorant. So it is difficult to select a panel with a sensitivity distribution similar to that of the population. The preferred method in the United Kingdom for screening panelists uses the actual odor to be tested as a key component. In France selection is carried out on the basis of the threshold for five standard odorants. In Germany a normal sense of smell is requested of persons between the age of 18 and 50 years, in the Netherlands no exact specifications are given. Anyway, an extreme clustering around the mean or towards the extremes has to be avoided. 

Brook trout [Salvdimsfontinalis] have both migratory (anadromous) and non-anadromous populations. Fish from each type were tested for their responses to home-stream water. Both preferred home stream over control water but were equally attracted to water from their home-stream and from an unfamiliar stream. Therefore, specific local odors may not be critical cues. Furthermore, anosmic fish made the same choices, indicating that taste may be involved. In the non-migratory population, responses to home-stream water were noted only in summer, not in winter (Keefe and Winn, 1991). 

Infants are able to acquire odor preferences on the first day of life. In one experiment, 12 male and 12 female white, healthy, full-term neonates were exposed to the odors of cherry or ginger on a pad taped to the inside of their crib for 24 hours. After this exposure, they were tested for preferences during active sleep (stage II). The behavior was videotaped and the duration of time oriented to each odor measured. Only the female neonates showed a preference for the familiar odor (Balogh and Porter, 1986). Therefore, even on the first day of life, females outperform males, as often described for children and adults (e.g. Yousem etal, 1999). 

The newborn rat is a natural split-brain preparation for olfactory learning protocols it can be trained to associate an odor with a milk reward via just one nostril. If the other nostril is tested, the animal shows no preference. However, at 12 days of age or later, the two sides of the brain are connected and a learned preference occurs with either nostril open. The information is stored M/nlaterally the animal shows unilateral preference if the commissure is cut after training. The maturation of the commissure pathways occurs between 6 and 12 days of age. In summary, unilaterally represented memories remain unilateral, even after bilateral retrieval processes have developed. The mnemonic storage capacity of the brain is increased by confining memory to one side (Kucharski and Hall, 1987). 

Woodmice, Apodemus sylvaticus, are able to walk when 11 days old and increase their locomotion between postnatal days 11 and 19. When moving about, they spend more time on home (nest) and male odor than on female odor and clean bedding. This difference is not observed if the woodmice are tested for the first time on day 15, suggesting a critical period for acquiring these odor preferences (Pontet and Schenk, 1988). 

Many fruits attract birds by colors, odors, and taste. After consuming the fruit, the birds will disperse the seeds to new habitat. Preference orders exist, and some fruits are rarely eaten by birds (see p. 306). For instance, the flavor of buckthorn, Rhamnus cathartica, ranked lowest of 11 fruit extracts tested in blackbirds, Turdus merula, and a song thrush, Turdusphilomelus (Sorensen, 1983). Least preferred fruits contain toxins that deter birds, perhaps to avoid seeds being dispersed to unfavorable habitat. For instance, it is disadvantageous for forest... 

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